Electric insulator



Q Ne PLASTIC. Cross Reference Patented February 9, 1904.

PATENT QFFICE,

THOMAS 'r. OF MONTOLAIR, NEW JERSEY, ASSIGNOR TO H. W.

' 'JOHNS-MANVILLE COMPANY, OF

OF YORK.

NEW- .Y RK, N. Y.', A CORPORATION ELECTRIC msuL 'ron.

SPECIFICATION forming part of Letters Patent No. 751,664, dated February 9 1904.

Application filed April 4, 1902. Serial No. 101,378- (No speoimena-) To all whom, it may concern.-

Be it known that I, THOMAS T. LYMAN, a citi-.

zen of the United States of America, and a .resident of Montclair, county of Essex, and

' 5 State of New Jersey, have invented certain new and useful Improvements in Electric Insulators, of which the follow'ingis a specifi cation. v

My invention relates to electric insulating 1 materials in general, and more specifically consists of an improved material for producing an insulation against the passage of an electric arc.

In many electric installations conductors I carrying heavy currents are separated by narrow spaces and the tendency of the current to are across the intervening space is diificult to restrain. This is especially so where the circuit between the adjacent conductors is being alternately made and broken by means of a moving conductor alternately thrown into and out d contact with the stationary conductors. My invention produces a material which when interposed between the conduc- 2 5 tors is most efficient in preventing the formation of such arcs. It is composed of asbestos plaster-of-paris, and silicate of soda, compressed and vitrified by heat, and with the addition, if desired, of any waterproofing 3 paint or other material applied to the surfaces.

My preferred process of making these insulators or arc-shields, as they are called in the trade, is the following: Plaster-of-paris is first mixed with an excess of short-fibered as- 3'5 bestosor other fireproof material. The usual proportions are about sixty parts of asbestos to twenty-five parts of plaster-ohm weight. This mixture iSTWOlH- tion of silicate of soda sufficient to render the esive an se -sustaining. Usually about fifteen parts, by weight, of the silicate of soda is suflicient. It is then mo in o a shape approximately that of md article and dried. The article so produced is then immersed in a bath of approximately three parfi of sillcate of sma to one part of Water by weig r s ath the article is com ressed in a mold and usually again sub- 'ected'to. the S1lICaEB-OT-SOdawSOlUtlOH Bath and me as'e ore. 18 s p in o 0*" may 5 be repeated according to the desired density and hardness of the completed article; but I have found onerepetition as above described to be usually sufficient. After the final compression I then fire the com ressed mass sub ecting it to a degree of Eea suflTc'ient to vitrify. This produces a hard and rigid mass of the shape given by the mold, which has the, propertyof resisting and preventing the passage of an electric are when inserted between the conductors, across which the arc might otherwise tend to establish itself. v The sheet or article so formed is then bufied'by rubbing with sandpaper, a file, or other abrading means and can be cut, drilled, turned, or otherwise' 5 operated on by tools in the usual way to give it the exact form desired. Either before or after this step in the process the article is rendered waterproof by painting it with liquid asphaltum or anysuitable waterproofing paint 7 or compound. Preferably the painting is done after the bufling, as that prepares the surface so that the paint will adhere more strongly. The advantages of the completed .article comprise its high resistance to the electric arc, its lightness and rigidity, and the ease with which it can be bored or otherwise worked with tools without splitting, breaking, or chip- The proportions of the constituent parts given above could be varied within limits, and I other fireproof materials might be substituted for asbestos, so long as the substitute material is fireproof and of sufficiently absorbent nature to take up the silicate-of-soda solution. Thepurpose of the plaster-of-paris is to give body and rigidity to the article, and other materials might be substituted for or added to the plaster-of-paris to produce this effect.

Having therefore described my invention, 9 what I claim as new, and desire 'to protect by Letters Patent, is 1. As a new article of manufacture, an insulator to prevent the formation of electric A Examine:

2. The herein-described process of produc-' of silicate of soda; second, drying the mass,

subjecting it to a bath of silicate-of-soda solution and compressing a suflicient number of times to produce the required degree of density and rigidity of the finished product; third, vitrifying the mass by heat.

3. The herein-described process of producing a material impervious to the passage of electric arcs which comprises the following steps: first, mixing plaster-of-paris with an excess of short-fibered asbestos in a solution of silicate of soda; second, drying the mass, subjecting it to a bath of silicate-of-soda solution and compressing a sufiicient number of times to produce the required degree of density and rigidity of the finished product; third, vitrifying the mass by heat; fourth, bufiing the surface of the mass.

4. The herein-described process of producing a material impervious to the passage of electric arcs which comprises the following steps: first, mixing plaster-of-paris with an excess of short-fibered asbestos in-a solution -of silicate of soda; second, drying the mass,

subjecting it to a bathof silicate-of-soda solution and compressing a sufficient number of times to produce the required degree of denbufling the surface of the mass; fifth, painting the surface of the mass with a waterproofing substance.

5. The herein-described process of producing a material impervious to the passage of electric arcs which comprises the following steps: first, mixing plaster-of-paris with an excess of short-fibered asbestos in a solution of silicate of soda; second, drying same, and subjecting it to a bath of diluted silicate of soda, third, compressing; fourth, drying; and again submitting to a bath of the silicate-ofsoda solution; fifth, again compressing; sixth, vitrifying by heat; seventh, bufiing the surfaces of the article produced by the foregoing process.

6. The herein-described process of producing a material impervious to the passage of electric arcs which comprises the following steps: first, mixing plaster-of-paris with an excess of short-fibered asbestos in a solution of silicate of soda; second, drying same, and subjecting it to a bath of diluted silicate of soda; third, compressing, fourth, drying; and again submitting to a bath of the silicate-of soda solution; fifth, again compressing; sixth, vitrifying by heat; seventh, buffing the surfaces of the article produced by the foregoing process; eighth, painting the surface of the mass with a waterproofing substance.

Signed at New York this 1st day of April, 1902.

THOMAS T. LYMAN.

Witnesses:

L. R; HOFF, F. SLWILLI MB. 

